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Ticket Q574202
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XPO - number of rows of a persistent table

created 11 years ago

Hi,
How I can quickly retrieve the number of rows of a persistent table?
I have written a code like this:
…
XPCollection coll = new XPCollection(uow, t);

num_rows = coll.Count;
…
And I can get the number of rows in coll.count but all table records are loaded into memory and it takes too much time.
Any suggestion?
Andrea

Comments (1)
SK SK
Saif Khan 11 years ago

    Taken from "Creating an XPCollection" - By default, the XPCollection retrieves all the objects which match the search criteria. To override this behavior, you can set the value of the TopReturnedObjects property to specify the maximum number of objects retrieved.

    1. If you are trying to sample test if XAF is is bringing back correct records then add a filter for a few records you are sure about and then compare that with your database.
    2. If you are looking to retrieve summary data for your app and you are using SQL Server, then flex SQL Server by using Database Views for summary and then calling those views in XAF…you can even join those views to other persistent classes.
    3. Consider DIRECT SQL QUERIES via XAF.
      Here are some ways to query the data-store https://documentation.devexpress.com/#XPO/CustomDocument2034
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    Answers approved by DevExpress Support

    created 11 years ago (modified 11 years ago)

    Hello Andrea,
    You can either follow Saif's suggestions in comments or use the Session.Evaluate method (find some example code in the end of this help article) to calculate the number of rows on the server side.

      Comments (2)
      AC AC
      Andrea Cavalleri 11 years ago

        Thanks to both.
        I will try!!!
        Andrea

        Dennis Garavsky (DevExpress) 11 years ago

          Welcome!

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          Other Answers

          created 11 years ago (modified 11 years ago)

          Hi,
          It works!!!

          public long GetNumRows(string table_name) { long num_rows = 0;
          using (UnitOfWork uow = new UnitOfWork(DataLayer)) { Type t = Type.GetType(table_name);
          if (t != null) { object count = uow.Evaluate(t, CriteriaOperator.Parse("Count()"), null);
          num_rows = Convert.ToInt32(count); } }
          return num_rows; }

          Andrea

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